Inlet unloader



Sept. 15, 1936. STENGER 2,054,640

INLET UNLOADER Filed June 19,- 1935 u 817/ ft- BY 2 mi.

HIS ATTORNEY.

Patented Sept. 15, 1935 UNITED STATES PATENT OFFICE to Ingersoll-RandCompany, Jersey City, N. J a corporation of New Jersey Application June19, 1935, Serial No. 27,285

2 Claims.

This invention relates to compressors, but more particularly to an inletunloader adapted to be interposed in the intake conduit of a compressor.

One object of the invention is to unload the 5.,- compressor wheneverthe storage pressure reaches a certain predetermined value.

Another object is to produce a compact and simplified unloader forcompressors which requires only a. few simple parts and which may becheaply operated and maintained.

Other objects will be in part obvious and in part pointed outhereinafter.

In the accompanying drawing forming a part of this specification and inwhich similar refer- 15. ence numerals refer to similar parts,.

Figure 1 is an elevation, in section, of an inlet unloader constructedin accordance with the practice of the invention and a compressor towhich it is applied, and v 20 Figure 2 is a transverse view takenthrough Figure 1 on the line 2-2.

Referring more particularly to the drawing, the inlet unloader which isdesignated, in general, by 20 is shown applied to a compressor 2| ofwhich 25 only so much is shown as will serve to illustrate a practicalapplication of the invention.

The compressor 2l comprises a cylinder 22 containing a piston 23 whichmay be actuated in any suitable manner for compressing the working sub-30 stance in the cylinder 22. On the end of the cylinder 22 is a head 24which serves as a closure for the compression chamber and is recessed toprovide an inlet chamber 25 and a discharge chamber 26.

Communication between the inlet chamber 25 and the compression chamberis controlled by a suitable inlet valve 21, and a valve 28 in the head24 controls communication between the compression chamber and thedischarge chamber 26. The

fluid intended to be compressed is conveyed into the inlet chamber 25 byan inlet conduit 29, and

a discharge conduit 30 communicating with the chamber 25 conveys thedischarge fluid from the compressor to a storage receiver 3|.

45 The inlet unloader 20 constructed in accordance with the practice ofthe invention and interposed in the intake conduit 29 of the compressor,comprises a casing 32 consisting of a pair of sections 33 and 34 whichmay be clamped to- 50 gather in face-to-face relationship, as by bolts35. The section 33 is recessed to provide a piston chamber 36 of whichone end constitutes a pressure chamber 31 which is connected with thereceiver 3| by a conduit 38. The piston chamber 55 36 contains areciprocatory piston 39 having a pressure surface 40 against whichpressure fluid may act for actuating the piston 39 in one direction.

The force of the pressure fluid acting against the pressure surface 40is opposed by a spring 4| 5 arranged in a recess 42 in the piston andacting against the casing section 34. The spring 4| is calibrated toyield at the predetermined maximum pressure which it is intended tomaintain in the storage receiver 3|, and the end of the spring 10projecting from the recess is guided by a stationary plug 43. The plug43 may be aifixed to the casing section 34 or,-. as shown, may seat upona packing member 44 clamped between the casing sections 33 and 34 toprevent leakage of fluid from the casing to the atmosphere.

The inlet conduit 29 or portions thereof which are connected to theunloader are threaded into the casing section 34. One conduit 29communicates with a passage 45 in the casing section 34 and the packingmember 44 and opening directly into the adjacent end of the pistonchamber 35, and a passage 46 in the casing section 34 and the packingmember 44 affords communication between the piston chamber and theportion of the conduit 29 connecting the unloader with the inlet chamber25 of the compressor. The arrangement of the passages 45 and 46 is suchthat the fluid medium flowing from supply to the compressor passesthrough the end of the piston chamber 36 so that said piston chamberconstitutes, in effect, a portion of the inlet supply line.

The packing member 44 is coextensive with the end surfaces of the casingsections and is substantially of the same conformation as the adjacentsurface of the section 34, that is, the passages in the packing memberare of substantially the same shape and size as the portions of thepassages 45 and 46 in the casing section 34. They are so located withrespect to the wall of the piston chamber and its axis that ample areasof surface of the packing member 44 will lie within the plane of thepiston to cooperate with the adjacent end of the piston for efiecting aseal on all sides of the passages and 46. 45

As will, therefore, be readily appreciated, when the piston 39 is seatedupon the packing member 44 the passages 45 and 45 will be thoroughlysealed to prevent leakage of fluid from supply into the compressor and,at the same time, an adequate 50 seal will be maintained around theperipheral edge of the piston 33 to prevent leakage of pressure fluidfrom the pressure chamber 31 into the compressor or to the source offluid supply.

Normally, during the operation of the compressor and when the pressurein the storage receiver 3| remains below the value at which the spring4| is intended to act, the said spring will maintain the piston 39 inthe open or raised position to permit free communication between thepassages and 46 through the piston chamber, and, therefore, between thecompressor and the source of fluid supply. The supply fluid will thenflow through the conduit 29, the passage 45, the piston chamber 36, thepassage 46 and the portion of the conduit 29 which connects the unloaderwith the compressor into the inlet chamber 25.

Upon passing through the valve 21 to the compression chamber the fluidis compressed and is discharged through the valve 28, the dischargechamber 26 and the conduit 30 into the storage receiver 3|. This mode ofoperation continues until the pressure fluid in the storage receiverreaches the value at which the spring 4| yields. The pressure fluidflowing from the storage receiver 3| through the conduit 38 into thepressure chamber 21 will then press the piston 39 against the packingmember 44, thus cutting off the further admission of fluid medium fromthe source to the compressor.

The pressure fluid thus acting against the ac tuating surface 40 pressesthe piston 39 against the packing member 44 with sufficient force to'prevent leakage of pressure fluid from the piston chamber 36 into theadjacent passages and also to prevent communication between the passages45 and 46. The compressor will then be completely unloaded and nofurther admission of fluid medium into the compressor will take placeuntil the pressure within the storage receiver 3| drops below thatexerted by the spring 4!. When this condition prevails in the storagereceiver the spring 4| will lift the piston 39 and thereby reestablishcommunication between the source of fluid medium and the compressor.

I claimi 1. An inlet unloader valve for compressors, comprising a casingconsisting of a pair of sections, there being a piston chamber in onesection and passages in the other section constituting portions of theinlet passage of the compressor and opening into the piston chamber, apiston in the piston chamber to control communication between thepassages and having a pressure surface, means for conveying pressurefluid to the pressure surface to actuate the piston for cutting offcommunication between the passages, and a packing member clamped betweenthe casing sections cooperating with the piston to prevent leakage ofsupply fluid through the piston chamber and to prevent leakage ofpressure fluid from the piston chamber and the passages along theconfronting surfaces of the casing sections to the exterior of thecasing.

2. An inlet unloader valve for compressors, comprising a casingconsisting of a pair of sections, there being a piston chamber in onesection and passages in the other section constituting portions of theinlet passage of the compressor and opening into the piston chamber, apiston in the piston chamber to control communication between thepassages and having a pressure surface, means for conveying pressurefluid to the pressure surface to actuate the piston in one direction forcutting off communication between the passages, a spring for actuatingthe plston to establish communication between the passsages, and apacking member between the sections to prevent leakage of fluid from thecasing to the atmosphere and cooperating with the piston to preventleakage of supply fluid from one passage toanother and to preventleakage of pressure fluid from the piston chamber to the passages.

AUGUST M. STENGER;

